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CITY OF EVERETT DRAINAGE CALCULATIONS (less than 5 acres) 05-Jun-92 <br />03:34 PM <br />Wa- Sang -Clearing -Plan, _LSA-2769________________________________________ <br />CALCULATION OF OUTLET SIZE <br />flow / orifice = 0.593 <br />For multiple ( 1.0 ) orifices, <br />SIZING ORIFICE FOR RESTRICTOR <br />d,ft d,inches <br />ft a, sf------------ <br />Orif. Elev. H, ----------- d,ft <br />_ <br />--------------- 0.34 <br />652.40 1.70 0.091 _ --1/8 ------------- <br />__ -----------4-- - <br />32.2 <br />area, a = Qdo / (.62 x (2 x g ** . <br />orifice diameter, d = ( 4/pi x a) <br />CALCULATION OF EMERGENCY OVERFLOW CAPACITY <br />Developed Discharge 25Y <br />------------------------------- r <br />Using least --equation for orifice: Q------------------ <br />= C x I x A storm <br />Q = 3.782 x (D)**2 x H**(1/2)--------------- <br />- <br />or --equation for a weir: Tc(o) = 15.0 minutes <br />Q= 9.739 x D x H**(3/2)---- I= 1.B10 in/hr <br />ft RO coeff, C 0.350 <br />2.200 <br />Min Head, F. = Area, A = 3.956 acres <br />Min. Dia., D = 0.667 ft Q _ 2.506 cfs <br />max capacity acit 2.493 cfs ----------------- <br />- <br />---------------------------- <br />